alternator woes

[jdeere86]

hey everyone

spring is here and tractors are running. my 140 with the 12v conversion seems to be draining the battery. Last year I was running her fine and would get the RPMS up to a certain level and then the alternator would self excite and start to charge. will say the needle was going left instead of right on my ammeter . maybe just wired backwards.

anyhow this year it will not self excite by getting the rpms up there.

any chance if i bought this harness i could wire a diode into it to get her to start charging

harness

wm_ADR9209.jpg (15.33 KiB) Viewed 461 times

a photo of the alternator

alternator

a wiring diagram that i followed -- notice for the warning light it says a diode may be used

diagram

[inairam]

when I have done Alternator conversion I usually put a separate ground wire on the alternator to the block mounting bolt. I do not like relying on the brackets and the hinge for the ground. It may not be your issue but a jumper wire would tell.

[Gary Dotson]

Yes, you can add a diode. You don’t need anybody’s harness to add a diode, just run a wire from you coil, diode in line, to the #1 terminal on the alternator. I got tired of having to remember to rev the engine, every time I started the tractors. Now, I just add the diode right from the start. Diodes are cheap, a small 2 amp will work nicely.

[inairam]

was the alternator listed as a one-wire self-exciting alternator? If so you should not need a diode.

[tst]

a diode just makes the current flow only in one direction , for a one wire alternator to work you need battery voltage at the alternator and that it spins fast enough to excite, with a meter it should be around 14-14.5 volts

[ShawnAgne]

I've found on my Cub that if it isn't grounded properly it won't excite. Haven't had the issue with the other two. I've thought about changing the alternator pully on the cub to a smaller one as I have to rev it fairly high. If I'm mowing isn't an issue. The 300 and 100 don't have to go as high for whatever reason.

[phill_mi]

My understanding is that originally the Delco 10si was 3-wire and that in some cases a 1-wire regulator has been installed in the 10si. So a 10si may or may not be 1-wire configured. I read that a 1-wire regulator typically has a wire at the base of the two pin connector shorting the pins. My tractor had a 10si wired by the PO's grandfather, long ago, as a 1-wire with nothing connected to the 2 pin connector. The battery slowly drained down and the ammeter rarely showed charging, and then very little even when reved. As an experiment with the tractor idling, I touched a jumper wire from pin 1 (on the left of the connector) to B+, momentarily and released it. The alternator started charging at full rate. I also could not see a jumper wire at the base of the connector. I added a diode with the cathode (barred end) to pin 1 of the connector and the anode of the diode to the ignition switch. I also ran a wire from pin 2 back to battery + to get real sensing of the battery, rather than connecting at the alternator B+. I used a piece of an extension cord that the dog had shredded and crimp spade clips to connect to the connector terminals. Any power diode with work as it only needs to pass a forward current of around half an amp and have a reverse blocking voltage of more than 20v.

[jdeere86]

Ended up running a wire from the coil with a diode inline to the #1 terminal on the alternator. Had to switch the wires on the back of the ammeter to get her to show positive. Initially it was showing -20. Its now showing a little under 10 ... is that enough of a charge? I know its a lot better than it being at zero. Couldn't have done it without this board. Thank you all very much!!

[JoeB]

A self exciting alternator will lose residual magnetism in the rotor if it not used for a long period of time. You can manually excite it and it should work again. There may be a youtube video or something to show this.

[Eugene]

Initially it was showing -20. Its now showing a little under 10 ... is that enough of a charge?

Watch the amp gauge during and immediately after engine start up. Amp gauge should initially show a significat charge then slowly drop down to below 10 amps. That's with only the ignition operating, no lightts, etc..

[Don McCombs]

I think I would consider putting some heat shrink tubing on that diode and the adjacent connectors.

[Gary Dotson]

I don’t pay a lot of attention to the amp output, it’s entirely dependent on load. Check the charging voltage, at the battery, should be 13.6 - 14.5. If it’s carrying good voltage, don’t worry what the ammeter shows.

[jdeere86]

Eugene. You are correct - after she fires the gauge shows a significant charge and then drops below 10. I'll get a tester from a buddy to check the charging voltage at the battery. My other friend who gave me the crimps said he'd come over and solder the connection after I see that it is working correctly. In the meantime I did wrap well with electrical tape and have since done some work out in the field without issues. Tomorrow or someday soon I hope to make a post inquiring about the possibility of if and when I should ever consider or will need to update the starter on this 59' . Right now it is a pull rod to start. Thank you all again

[staninlowerAL]

.....Tomorrow or someday soon I hope to make a post inquiring about the possibility of if and when I should ever consider or will need to update the starter on this 59' . Right now it is a pull rod to start. Thank you all again

I had starter shop successfully replace the "nub" connection on a 6v cub starter with a threaded bolt type connector to use a ring terminal type cable. Added an electrical solenoid and you're back to work. The main problem is finding a shop who still does the "in house" repairs that can remove the "nub" and solder in the bolt . Seems like most of those craftsmen are gone. JMHO Stan

[Gary Dotson]

If you’re looking to ditch the pull rod, you can do as Stan mentioned but if you’re ok with the pull rod, you will probably have no issue with the 6 volt starter, as long as it’s in good condition. They are really quite robust.